Electronic devices generally include a variety of different display and cover components, including front and back glasses (or cover glasses), display windows, touch screens, track pads, camera and lens covers, and other internal and external cover components where optical features, durability and reliability are design issues. In use, these components are subject to a wide range of different environmental effects, including physical and electrical contact, temperature extremes, scratching, and impact.
These effects raise a number of design issues, particularly where internal and external components are subject to different combinations of environmental conditions and performance requirements. Associated design and engineering considerations include tradeoffs between shock and impact resistance, machinability, temperature stability, and thermal and electromagnetic properties including resistance, conductance, and permeability.